Latest / The Indie Hacker Podcast with Fexingo: Solo Developers, SaaS Side Projects, and Independent Tech / How a Solo Dev Built a SaaS Via Cold Email
Transcript
- Lucas: So cold email. We've all received hundreds of them. But a solo developer used it to build a SaaS from scratch. No ads, no social media, no content marketing. Just a carefully crafted inbox strategy. Luna: Wait, cold email for a SaaS product? That's usually reserved for agencies or freelancers. How does that even work for software? Lucas: That's exactly what I thought. But Sarah Chen, a former data analyst turned indie hacker, proved it's possible. She built a document-review tool for small law firms and got her first 50 customers solely through cold email. Luna: Okay, I'm intrigued. What was the tool? And why law firms? Lucas: The product is called BriefCheck. It automatically reviews legal briefs for formatting errors, citation consistency, and missing case references. Small law firms — firms with five to twenty attorneys — often don't have dedicated paralegals for that. Sarah saw the gap when a friend who's a solo immigration attorney complained about spending hours on formatting. Luna: So she built a solution for one specific pain point. That's classic indie hacker. But cold emailing lawyers? That's a tough crowd. Lucas: Tough but targetable. She didn't blast generic templates. She researched each firm. Found the partner who handles hiring or tech decisions. Then sent a personalized email referencing something specific — a recent case win, a blog post they wrote, a legal conference they spoke at. Luna: Give me an example of what that email actually looked like. Lucas: She shared one on her blog. Subject line: 'Quick question about your brief prep.' Body: 'Hi, I saw your firm's win in the Smith vs. County case — impressive work. I'm a solo developer who built a tool that cuts brief formatting time by 40 percent. I noticed your firm doesn't have a dedicated paralegal listed on the website. Would you be open to a five-minute demo this week? No pitch, just showing you the tool.' Short, specific, low-pressure. Luna: That's good. She's demonstrating research and empathy. What was the reply rate? Lucas: She tracked everything meticulously. Over the first three months, she sent 450 emails. 54 replied — that's a 12 percent reply rate. Of those, 18 turned into paying customers. That's a 4 percent overall conversion, but 33 percent of replies converted. At $79 per month, that's about $1,400 monthly recurring revenue from that batch. Luna: Four-fifty emails for eighteen customers. That's a lot of manual work for a solo dev. Lucas: It is. But she argues it's more sustainable than running Facebook ads or trying to rank on Google. Each email took about three minutes to research and write. So roughly 22 hours of work for $1,400 MRR. She then automated the follow-up sequence using a simple CRM. Luna: What did the follow-ups look like? I imagine a lawyer gets a lot of cold email. Lucas: Three-part sequence. Day one: the initial email. Day three: a short follow-up saying 'Just circling back — happy to show you the tool in under five minutes.' Day seven: a final email with a case study from another firm that saved 10 hours a week. Then she stopped. No further contact. Luna: And that worked? No one got annoyed? Lucas: She had a few negative replies — maybe five out of 450. But most either ignored or replied politely. The key was the personalized first email. She never sent a template to more than 20 people, and she changed the subject line for each batch. Luna: So the product itself was good. But what happened when she scaled beyond the first 50 customers? Cold email doesn't seem scalable to thousands. Lucas: She hit a ceiling around 120 customers. At that point, she had to hire a part-time virtual assistant to handle research and send more emails. But she also started getting referrals. One firm told another. Her churn was low — about 3 percent monthly — because the tool saved real time. Luna: That's interesting. The cold email got the flywheel started, then word of mouth took over. I think a lot of founders underestimate how much you can do with just a list and a personalized message. Lucas: Exactly. And Sarah's story shows that cold email isn't dead — it's just misunderstood. Most people send spam. She sent research-backed, relevant pitches. And she targeted a niche where the decision maker was easy to identify and the pain point was acute. Luna: That's a great point. It's not about volume; it's about relevance. You can send a hundred emails to the wrong people and get zero replies, or forty emails to the right ones and get five customers. Lucas: Right. And speaking of relevance — a handful of listeners help keep this show ad-free by chipping in on buy me a coffee dot com slash fexingo. It's literally what funds the time we spend researching stories like Sarah's. So if this episode gave you something actionable, that's where you can support the work. Luna: Yeah, it's a small group that makes a big difference. No ads, no sponsors — just listeners who find value here. Anyway, back to Sarah's story. Lucas: So after the first 50 customers, she refined her pitch. She realized immigration attorneys had a much higher conversion rate than, say, real estate lawyers. So she doubled down on that sub-niche. She created a landing page specifically for immigration firms, with testimonials from two immigration attorneys. Luna: That's smart. She used the data from her cold email campaigns to identify the best segment. Almost like a live A/B test on the entire market. Lucas: Exactly. And she shared her numbers openly. Her conversion rate for immigration firms was 8 percent — double the average. So she spent 80 percent of her email efforts on that niche. Within six months, she hit $10,000 MRR. Luna: That's impressive for a tool that solves a relatively boring problem. But I think that's the lesson: boring problems in overlooked niches are goldmines for indie hackers. Lucas: Absolutely. Everyone wants to build the next AI social media platform. Sarah built a document checker for lawyers. And she's making a comfortable living without a sales team or ad budget. Luna: What about the actual product? Did she build it with a specific tech stack that made it easy to iterate based on feedback? Lucas: She used Python with a simple React frontend. The core logic was a set of rules for legal citation formats — Bluebook, ALWD, that kind of thing. She also integrated with a PDF parsing library. Her first version took two months to build. She launched with just the formatting check, then added citation validation based on user requests. Luna: So she didn't overbuild. Launched with a minimal feature set and expanded based on what cold email prospects asked for during demos. That's textbook lean startup. Lucas: Exactly. And because she was doing demos constantly, she had a direct line to what customers actually needed. One attorney asked for a feature that checks if a cited case has been overturned. She built it in a weekend. That feature became a major selling point. Luna: So cold email wasn't just for acquisition — it was also a feedback channel. That's something I think a lot of founders miss. They treat email as a one-way broadcast instead of a conversation starter. Lucas: Right. Sarah treated every reply — even the rejections — as data. She categorized why people said no. 'Not interested' was common. But some said 'we already have a solution' or 'too expensive.' She used that to adjust her pricing and positioning. Luna: What was her pricing journey? She started at $79 per month? Lucas: She tested a few tiers. Initially $49 for solo attorneys and $99 for firms. But she found that solo attorneys churned faster — they'd use it for a case and then cancel. Firms stayed longer. So she simplified to one price: $79 per month for up to five users. That reduced confusion and increased average revenue per customer. Luna: That makes sense. Firms have more consistent demand. So what's her ARR now? I read somewhere she hit six figures. Lucas: As of early this year, she's at about $140,000 annual recurring revenue. She's still solo, but she hired a part-time customer support person. She spends about 10 hours a week on email outreach and the rest on development and support. Luna: That's a solid lifestyle business. And it all started with cold email. I think there's a myth that you need a huge audience or viral launch to build a SaaS. Sarah disproves that. Lucas: Completely. She had zero followers, zero blog traffic, zero ad spend. Just a spreadsheet of law firm websites and a willingness to send personalized emails. It's a blueprint that any solo developer can replicate if they pick the right niche. Luna: What advice would she give to someone starting out? I imagine the biggest hurdle is the fear of rejection. Lucas: She wrote a thread about that. Her advice: start with ten emails. Don't try to build a perfect product first. Send ten emails describing the problem you want to solve. See if anyone replies. If they do, you have a signal. If not, pivot. She spent a month just emailing lawyers about their document pain points before writing a single line of code. Luna: That's actually really smart. Validate the market through cold email before building anything. It's like customer discovery but with a higher response rate than surveys. Lucas: Exactly. And lawyers are a great test case because they're busy and opinionated. If you can get a lawyer to reply, you know you're onto something. Sarah's approach is a masterclass in combining sales and product development for indie hackers. Luna: It's also a reminder that 'indie' doesn't mean you have to do everything alone. You can use email as a tool to build relationships, not just transactions. I think that's a lesson that applies beyond SaaS. Lucas: Totally. Cold email gets a bad rap because it's associated with spam. But when done right — with research, empathy, and a real solution — it's one of the most direct ways to find your first customers. Sarah's story proves it. Luna: And she's still at it. I checked her blog, and she's now experimenting with LinkedIn outreach combined with email. Might be a new angle for a future episode. Lucas: Definitely worth following. For now, the takeaway: if you're building a B2B SaaS, don't overlook cold email. It might be the only channel you need.